vBulletin 3.0.7 mysql error number: 0 Link-ID == false, connect failed

[Boss-Hog]

Can anyone help me out with the following error message on vBulletin 3.0.7? My server load seems to be pretty stable (all three numbers are consistently under 1.0 and usually under 0.5) but I'm seeing this:

Database error in vBulletin :


Link-ID == false, connect failed
mysql error:


mysql error number: 0

That's the report I get via email and they are all producing this same mysql error message/number. I'm seeing it when all different sorts of files are being accessed (showthread.php, forumdisplay.php?do=markread, index.php) and from many different users. I have attached a report of the file the errors are being logged to (which is showing displaying other database errors, actually), as well as a screenshot of what the user sees when this problem occurs. When the problem does happen, hitting refresh/reload seems to load the page the user was trying to access in the first place, so it's not as if the site is down for a while...just momentarily unable to connect. Thanks!

Boss

[Steve Machol]

This error means that either:

1) The db info in your config.php file is wrong (in which case your forums won't work at all.)

2) That user doesn't have permission to access the database listed in config.php.

3) The database doesn't exist.

4) MySQL isn't accepting new connections. (The server could either be down or has reached it's maximum connections limit - either on the server level or user level.)

If you are sure your config.php info is correct, then you will need to contact your host about this.

Note, many servers are being probed for the phpBB worm these days and the MySQL server is being overloaded. This could account for these errors.

[Boss-Hog]

This error means that either:

1) The db info in your config.php file is wrong (in which case your forums won't work at all.)

2) That user doesn't have permission to access the database listed in config.php.

3) The database doesn't exist.

4) MySQL isn't accepting new connections. (The server could either be down or has reached it's maximum connections limit - either on the server level or user level.)

If you are sure your config.php info is correct, then you will need to contact your host about this.

Note, many servers are being probed for the phpBB worm these days and the MySQL server is being overloaded. This could account for these errors.

I can rule options 1-3 out with 100% certainty. Here's my host's response to the fourth possibility:

I've looked through the logs (been monitoring that thread) - but I dont see _any_ hiccups in the mysql server... not sure where the issue is happening. Still looking

Any other ideas why this would be happening periodically for different users? As always, thanks for your help.

[Steve Machol]

Those are all the known causes of this issue. If it's not 1-3, then the problem is at the server level.

[Boss-Hog]

Those are all the known causes of this issue. If it's not 1-3, then the problem is at the server level.

Well, I don't have a vB specified limit on the number of Simultaneous Sessions or *NIX Server Load Limit because like I said, my server load numbers appear to be very stable. So, in that case, you're saying the problem is a problem with the server load?

[Steve Machol]

No I didn't say the problem is with the server load, although that is certainly one possible cause of many. When this happens, the problem is because the MySQL server cannot be connected to. If your config.php info is correct (which I have no doubt is true) then the only other cause of this problem is at the server level.

[Torqued]

I had a problem with those errors when I was having intermittent DNS issues. I had moved to a new server and all of my "old" info didn't get changed in DNS. Try seeing if someone that gets that error can run tracert for your domain to rule out DNS issues.

[Boss-Hog]

My site just moved to a new server, so obviously, the DNS settings had to be updated. That sounds similar to what happened to you, huh?

I had a problem with those errors when I was having intermittent DNS issues. I had moved to a new server and all of my "old" info didn't get changed in DNS. Try seeing if someone that gets that error can run tracert for your domain to rule out DNS issues.

[Torqued]

My site just moved to a new server, so obviously, the DNS settings had to be updated. That sounds similar to what happened to you, huh?

Yep.

[Boss-Hog]

Yep.

Here's my host's response to the question: "Could it be a DNS issue, as was later allueded to?"

no, not really a possibility or it'd be happening for a LOT more people and it would be noticed by HostPC and several government sites.

He also said:

I think the comment:

"Note, many servers are being probed for the phpBB worm these days and the MySQL server is being overloaded. This could account for these errors."


might be a possibility ... as soon as they find there are none on that server, it'll calm down.


I've optimized MySQL to accept more connections to compensate IF that's the issue.

[Torqued]

Here's my host's response to the question: "Could it be a DNS issue, as was later allueded to?"

It was a DNS issue for me because there was still an old entry for my domain that was pointing to my old IP. I was their only hosting account that was having problems because I had 2 dns entries for my domain pointing at different IP's.

Are you still getting the errors? I still say it could be a DNS issue if your change had not fully propogated. In my case, I would be browsing my site just fine, but would be getting those error emails from other people trying to hit the site because they were resolving the domain to the "wrong" IP.

[Marco van Herwaarden]

Are you still getting the errors? I still say it could be a DNS issue if your change had not fully propogated. In my case, I would be browsing my site just fine, but would be getting those error emails from other people trying to hit the site because they were resolving the domain to the "wrong" IP.

That sounds strange to me. If PHP wants to connect to MySQL, this is a server process, no clientside DNS involved in that i think.

[Torqued]

That sounds strange to me. If PHP wants to connect to MySQL, this is a server process, no clientside DNS involved in that i think.

This was related to a server move.

My "old" directory containing vBulletin files was still on the old shared IP box. As such, it had a different config for mysql. When the DNS would point to the wrong shared IP box, it was trying to connect to the DB that was no longer on that shared box.

My site's IP would flip flop between the "wrong" shared IP box and the "right" shared IP box due to there being 2 conflicting entries in my webhost's DNS.

When the account was moved from DNS-Server1 to DNS-Server2 the DNS on the DNS-Server1 server was not completly wiped out. I went ahead and manually wiped the DNS out of both servers and then added it back to the DNS-Server2 server only. This should fix the issues with the DNS hopping back and forth.

[Boss-Hog]

Here's a response from my host on the matter:

Here's the mysql optimization we've done. Post it in vbulletin forums, and see if they have any further suggestions. I still dont see it as a DNS issue, this is definately a MySQL issue (and it's interaction with VB)


[mysqld]
skip-locking
skip-innodb
query_cache_limit=1M
query_cache_size=32M
query_cache_type=1
max_connections=500
interactive_timeout=100
wait_timeout=100
connect_timeout=10
thread_cache_size=128
key_buffer=16M
join_buffer=1M
max_allowed_packet=16M
table_cache=1024
record_buffer=1M
sort_buffer_size=2M
read_buffer_size=2M
max_connect_errors=10
# Try number of CPU's*2 for thread_concurrency
thread_concurrency=2
myisam_sort_buffer_size=64M
log-bin
server-id=1


[safe_mysqld]
err-log=/var/log/mysqld.log
open_files_limit=8192


[mysqldump]
quick
max_allowed_packet=16M


[mysql]
no-auto-rehash
#safe-updates


[isamchk]
key_buffer=64M
sort_buffer=64M
read_buffer=16M
write_buffer=16M


[myisamchk]
key_buffer=64M
sort_buffer=64M
read_buffer=16M
write_buffer=16M


[mysqlhotcopy]
interactive-timeout

[Steve Machol]

It's difficult to evaluate just the my.cnf info without knowing a while lot of other information about this server. Here is the typical info we need:

http://www.vbulletin.com/forum/showthread.php?threadid=70117